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Corrosion layers removal in low-pressure plasma
Kujawa, Adam ; Grossmannová, Hana (referee) ; Krčma, František (advisor)
A plasmachemical reduction of corrosion layers on copper was studied. In this case two series of copper samples were prepared and putted in two corrosive environments for one week. The first corrosive environment contained a concentrated nitric acid and the second environment contained a concentrated sulfuric acid. Samples thus prepared were ready to be plasmachemicaly treated. The plasmachemical reductions took place in low-temperature, low-pressure, non-isothermal, high-frequency-inducted hydrogen plasma on the Faculty of Chemistry in University of Technology in Brno. The discharge was generated in continual or pulse mode with changeable pulse ratio. To monitor the reduction process an optical emission spectroscopy was used. The radiation from plasma discharge was measured by an optical spectrometer in the intervals of 1 to 10 minutes. An object of our concern in collected spectrum was the radiation of OH radicals with electromagnetical wavelenght in a range of 305 – 330 nm, and which were produced in a reaction between the hydrogen radicals and the oxygen atoms, contained in the corosion layers. A rotation temperature of plasma was calculated from the spectrums of OH radicals in a dependence of discharge conditions. Gathered findings will give us a better knowing of this conservation technique, that is used for treatment of the corroded surfaces of the archeological artifacts, and will also allow more provident appliance of this method on a copper historical objects.
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Plazmachemical reduction of corrosion layers on copper samples
Kujawa, Adam ; Slavíček,, Pavel (referee) ; Mazánková, Věra (advisor)
The object of study in present diploma thesis is the plasmachemical reduction of corrosion layers on copper. This process is based on reductive properties of low pressure hydrogen plasma. In this case three series of copper samples were prepared and corroded in different corrosion environments in order to create three kinds of artificial corrosion layers. In the first step the copper coupons were properly grinded in order to achieve a defined surface roughness. In the next step the coupons corroded for 12 days in vapours of three concentrated acids – HCl, HNO3, and H2SO4. SEM/EDX analysis was carried out in order to characterise the grown corrosion layers on copper coupons, which showed us the presence of nitrogen, oxygen, chlorine and sulphur in different chemical forms in corrosion layers. The most significant part of this work was the plasmachemical treatment of corroded copper samples. Pure hydrogen was used as a reaction gas under the pressure of about 200 Pa and 50scc/m flow rate. The discharge was generated in quartz-glass reactor by using RF generator under the different power and mode settings. Optical emission spectroscopy was used to detect the intensity of plasma radiation. The value of integral intensity of OH radicals represented quantitative ablation of oxygen from a corrosion layer. OH radicals were the main products of reaction between hydrogen radicals (from plasma) and oxygen in corrosion layer. Time of increasing of OH radicals intensity was different for coupons from different corrosion environment and was also related to used power of generator and mode. The process was finished when the OH radicals intensity decreased to 10% of reached maximum. Sample temperature was an important indicator of sample protection against metallographic changes. The analyses XRD and SEM/EDX on corroded and treatment samples were performed. The analyses show that the decrease of main corrosion agents as chlorine and oxygen was achieved by hydrogen plasma treatment. The corrosions as well as their removal are a very complex problem and the plasmachemical treatment of metal objects is an efficient method for the removal of corrosion layers as compared to conventional conservations methods mainly due to a significant reduction of treatment time.
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Plazmachemical reduction of corrosion layers on copper samples
Kujawa, Adam ; Slavíček,, Pavel (referee) ; Mazánková, Věra (advisor)
The object of study in present diploma thesis is the plasmachemical reduction of corrosion layers on copper. This process is based on reductive properties of low pressure hydrogen plasma. In this case three series of copper samples were prepared and corroded in different corrosion environments in order to create three kinds of artificial corrosion layers. In the first step the copper coupons were properly grinded in order to achieve a defined surface roughness. In the next step the coupons corroded for 12 days in vapours of three concentrated acids – HCl, HNO3, and H2SO4. SEM/EDX analysis was carried out in order to characterise the grown corrosion layers on copper coupons, which showed us the presence of nitrogen, oxygen, chlorine and sulphur in different chemical forms in corrosion layers. The most significant part of this work was the plasmachemical treatment of corroded copper samples. Pure hydrogen was used as a reaction gas under the pressure of about 200 Pa and 50scc/m flow rate. The discharge was generated in quartz-glass reactor by using RF generator under the different power and mode settings. Optical emission spectroscopy was used to detect the intensity of plasma radiation. The value of integral intensity of OH radicals represented quantitative ablation of oxygen from a corrosion layer. OH radicals were the main products of reaction between hydrogen radicals (from plasma) and oxygen in corrosion layer. Time of increasing of OH radicals intensity was different for coupons from different corrosion environment and was also related to used power of generator and mode. The process was finished when the OH radicals intensity decreased to 10% of reached maximum. Sample temperature was an important indicator of sample protection against metallographic changes. The analyses XRD and SEM/EDX on corroded and treatment samples were performed. The analyses show that the decrease of main corrosion agents as chlorine and oxygen was achieved by hydrogen plasma treatment. The corrosions as well as their removal are a very complex problem and the plasmachemical treatment of metal objects is an efficient method for the removal of corrosion layers as compared to conventional conservations methods mainly due to a significant reduction of treatment time.
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Corrosion layers removal in low-pressure plasma
Kujawa, Adam ; Grossmannová, Hana (referee) ; Krčma, František (advisor)
A plasmachemical reduction of corrosion layers on copper was studied. In this case two series of copper samples were prepared and putted in two corrosive environments for one week. The first corrosive environment contained a concentrated nitric acid and the second environment contained a concentrated sulfuric acid. Samples thus prepared were ready to be plasmachemicaly treated. The plasmachemical reductions took place in low-temperature, low-pressure, non-isothermal, high-frequency-inducted hydrogen plasma on the Faculty of Chemistry in University of Technology in Brno. The discharge was generated in continual or pulse mode with changeable pulse ratio. To monitor the reduction process an optical emission spectroscopy was used. The radiation from plasma discharge was measured by an optical spectrometer in the intervals of 1 to 10 minutes. An object of our concern in collected spectrum was the radiation of OH radicals with electromagnetical wavelenght in a range of 305 – 330 nm, and which were produced in a reaction between the hydrogen radicals and the oxygen atoms, contained in the corosion layers. A rotation temperature of plasma was calculated from the spectrums of OH radicals in a dependence of discharge conditions. Gathered findings will give us a better knowing of this conservation technique, that is used for treatment of the corroded surfaces of the archeological artifacts, and will also allow more provident appliance of this method on a copper historical objects.
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